To support rock in tunnel construction and mining, it is nowadays rather common to use a rockbolt in which the end to be pushed into the hole is provided with locking members, such as a wedge anchor, which is then tightened with a support flange and a nut included in the bolt. To fix the bolt firmly to the rock and to protect it from corrosion, the space between the bolt and the hole wall has to be filled with soldering material, such as concrete. In practice, it has been difficult to implement soldering, which has led to development of a new bolt structure, which is described in U.S. Pat. No. 5,636,945. In this solution, a tube to be arranged around the bolt is fastened to a support flange, which will rest against the rock surface, and connected to the feed chamber attached to the flange. There is a hole on the side of the feed chamber, and soldering material can be fed into the feed chamber through this hole and a nozzle for soldering material pushed into the hole and further inside the above-mentioned tube through the feed chamber. From the tube, the soldering material flows along an annular channel between the tube and the bolt to the end of the bolt and back to the beginning of the tube along an annular channel between the tube and the hole walls. Thus the free space can be filled with soldering material reliably and efficiently, and it can be noted that the space is filled up as concrete starts to penetrate out of the hole. According to the above-mentioned patent, the flange is provided with a hole through which the soldering material that has got between the flange and the rock can penetrate, and thus it can be noted that the hole is filled up.
In this bolt structure it is, however, difficult to fill the space with soldering material. To feed soldering material into the feed chamber reliably, the nozzle for soldering material has to be pushed manually into a hole on the side of the feed chamber. This is laborious, difficult and slows down the bolting considerably. Furthermore, in most cases the worker has to be in a cage or the like to reach to the bolt, even though the bolt could be fed and the nut tightened mechanically with a bolting device. The above-mentioned manual stages also pose a considerable safety risk because the worker has to work under a rock that has not been reinforced.
An object of the present invention is to provide an arrangement which enables filling of a drill hole with soldering material safely, easily and, thanks to mechanization, economically using a rockbolt provided with a guide tube and a feed chamber. The arrangement according to the invention comprises a sleeve-like nozzle which can be placed tightly around the feed chamber so that the feed hole of the feed chamber is connected to the inner space of the nozzle, and the arrangement comprises means for feeding soldering material inside the nozzle and therethrough into the feed chamber, and means for placing the nozzle around the feed chamber.
The invention is based on the idea of using, instead of a nozzle for soldering material which is difficult to push tightly into a hole provided on the side of the feed chamber, a sleeve-like nozzle which in the operating position surrounds the feed chamber and in which the inner circumference of the sleeve tightens against the outer surface of the feed chamber and/or the front edge of the sleeve tightens against the flange so that soldering material, when fed into the sleeve, cannot penetrate from between the sleeve and the flange or from between the sleeve and the outer surface of the feed chamber. Instead, the material penetrates into the guide tube through the hole on the side of the feed chamber and further inside the upper part of the bolt, and back down from between the guide tube and the drill hole, which was the intention in the design of the bolt. Another basic idea is that the sleeve-like nozzle is connected to mechanical means which can place it on top of the feed chamber so that soldering material can be fed safely by feeding means of soldering material attached to the nozzle, the feeding means being guided by actuators provided in the usual place on the base of the drilling device. Thus the user does not need to move from his position to feed soldering material.